DE19537562A1 - Dewatering centrifuge with surrounding spray dryer having seal between housing and centrifuge drum - Google Patents

Abstract

Sludges are dewatered and dried in a solid bowl screw centrifuge, the ejection zone for densified material forming the dispersion member of a spray dryer, with fixed housing surrounding the centrifuge drum. The dryer housing is sealed at both end faces (15) against the rapidly rotating centrifuge drum by a seal comprising a rotary sealing ring (17) and a flexible expansion joint (18). The rotary seal is not attached to the dryer housing but is connected to the housing by displaceable sealing members (24). Pref. the rotary seal is fastened to the same support as the centrifuge rotor e.g. frame (22). Rotary seal is pref. a non-contact seal with narrow gap e.g. labyrinth seal or a contact seal e.g. sliding ring seal, not attached to the dryer housing. The device avoids damage due to mechanical contact with rotating faces and accommodates expansion, contraction and vibration.

Description

The invention is directed to a dewatering device for dewatering and drying sludge with a centrifuge to separate a sludge shaped solid-liquid mixture to a thick matter with an inlet for the supply of the sludge-like solid-liquid mixture, with mind least an outlet for the separated liquid and an outlet for the separated solids, the solids discharge zone of the centrifuge the disper The atomizer dryer forms a yawing device, with means for deflecting the flight web of the centrifugally thrown off in dispersed form as a particle veil moist solid particles in the axial direction of the centrifuge, with at least one Hot gas inlet and at least one outlet for the dried solid particles and the drying gas.

Such a drainage and drying device is from the EP 0591299 known.

In this known dehumidifier, the high speed the centrifuge ejection, preferably a solid bowl screw trifuge, radially hosed moist solid particles in the size 0.3-3 mm by suitable means, for example deflection plates or by suitable Gas flow deflected in the axial direction of the centrifuge and from the gas flow guided on a spiral trajectory in the drying room. Here are the hosed solid particles from the drying gas with high relative speed liquid washed and dried. The drying room is a concentric rin gray. It is made from the outer dryer housing, the inner rotie the drum shell of the centrifuge or an inner drum that reverses Forming housing and the two housing end walls.

The outer walls of the concentric drying room are not rotating and have to face the rotating parts of the internal centrifuge be sealed at least at one point.

The rotary seal between the centrifuge rotor and the surrounding dry nergehäuse must have a high relative speed, a gas differential pressure between between inside and outside, as well as displacement movements from thermal expansion and bridge vibrations and endure. The escape of gases from the Dryer interior to the outside or the entry of false air from the outside to inside should be prevented or minimized by the seal.

It has now been shown that, in particular due to thermal expansion during heating Processes during the start phase, with vibrations, or with temperature changes  of the dryer housing the sealing gap between non-rotating Modify housing parts and rotating centrifuge parts in an impermissible manner different. This can cause temporary contact between the sealing surfaces and loading damage or destruction of the seal.

To avoid this, the gap width must be chosen so large that despite Thermal expansions and displacements of the dryer housing are not appropriate non-contact seals.

Another disadvantage is that the gap is also caused by vibrations of the Drainage centrifuge inside the dryer changes as the spin de and the non-rotating part of the seal on different seals carriers are attached.

Too large a sealing gap is particularly important when the centrifuge dryer is in operation Inert gas atmosphere of great disadvantage, since the Oxygen content of the inert dryer gas is increased significantly.

It is an object of the invention, the known drainage and Develop the drying device so that when the centrifuge dryer is in operation the disadvantages mentioned no longer occur.

The task is solved with the measures of the marking part of claim 1.

Advantageous embodiments of the invention are given in the subclaims ben.

Due to the inventive design of the seal, the seal gap should be kept very close without the risk of it becoming too mecha African touches of the rotating with non-rotating active surfaces of the Rotary seal comes and its damage and destruction. Another The advantage is that even uncontrollable larger displacement and stretching movements of the dryer housing during the heating or cooling phase of the Centrifuge dryer or stronger vibrations during operation the sealing Do not influence the function despite the narrow gap of the rotary seal. An exit from internal gases or solids or an entry of false air into the inert Drying gas is almost completely prevented by the narrow sealing gap.

Further details, advantages and features of the invention will become apparent from the examples of management explained in more detail using schematic drawing figures.

Show it:

Fig. 1 shows a centrifugal dryer with a housing seal in longitudinal section;

Fig. 2 is a non-contact labyrinth seal for a centrifugal dryer,

Fig. 3 is a non-contact thread feed seal for a centrifugal dryer,

Fig. 4 is a non-contact thread feed seal with top thread,

Fig. 5 is a non-contact seal with flat grooves.

The centrifuge dryer shown in Fig. 1 consists of a centrifuge, in the example shown from a solid bowl screw centrifuge ( 1 ) which is encased by a housing ( 2 ) of an atomizing dryer. A jacket ( 4 ) is arranged around the centrifuge drum ( 3 ).

The dryer housing ( 2 ) and the jacket ( 4 ) form a concentric Rin graum ( 5 ) through which the drying gases loaded with the solid particles are passed. The drying gas ( 8 ) is fed through the tangential gas inlet ( 12 ), detects the dewatered solid ( 9 ), dries it and transports the solid particles in spiral paths through the drying chamber ( 5 ) to the outlet channel ( 13 ). The separated in the centrifuge ( 1 ) water is discharged in the liquid chute ( 14 ).

The dryer housing ( 2 ) is sealed on the two end walls ( 15 ) and ( 16 ) against the rapidly rotating centrifuge drum ( 3 ). The gap ( 19 ) of the rotary seals is formed by the centrifuge drum ( 3 ) and the sealing ring ( 17 ) which, like the drum bearing blocks ( 21 ), is rigidly attached to the base frame ( 22 ). By fastening the two effective surfaces ( 3 ) and ( 17 ) forming the sealing gap ( 19 ) to the same support ( 22 ), the sealing gap ( 19 ) is guided precisely and stably. The centrifuge drum (3) is cold and when flowing through the drying room (5) with hot gases (8) by the applied suspension (7) and does not expand, whereas the axial nergehäuse with hot gas (8) through which flow Trock (2) in and greatly extends in the radial direction.

The displacement movements of the two housing end walls ( 15 ) and ( 16 ) are compensated for by a gastight flexible compensator ( 18 ) or an elastic membrane ( 25 ) or a displaceable sliding ring ( 30 ) relative to the rigidly attached sealing ring ( 17 ), so that the sealing gap ( 19 ) is not changed.

Fig. 2 shows in detail a non-contact labyrinth seal for a centrifuge gene dryer, which connects the rigidly to the frame ( 22 ) sealing ring ( 17 ) with the axially and radially shifting dryer front wall ( 15 ), gas-tight by a compensator ( 18 ). The flexible compensator ( 18 ) is e.g. B. by tensioning tapes ( 23 ) or other fasteners both with the sealing ring ( 17 ) and with the end wall ( 15 ) gas-tight.

The sealing gap ( 19 ) between the tips ( 24 ) of the labyrinth seal and the ro centrifuging drum surface ( 3 ) can be kept very narrow (0.3-0.5 mm) because the displacement movement of the end wall ( 15 ) does not the La byrinth seal is transferred.

All non-rotating parts are hatched right, all rotating parts are left hatched.

Fig. 3 shows a non-contact thread seal for a centrifuge dryer, the z. B. in the dryer room to the right of the end wall ( 15 ) has a negative pressure.

The sliding and sliding movements of the dryer front wall ( 15 ) during the heating or cooling phase of the dryer housing are compensated for by a sheet metal ring ( 26 ) which is sealed by heat-resistant O-rings ( 27 ) and both on the dryer front wall ( 15 ) and on rigid attached sealing ring ( 17 ) can slide. The narrow gap ( 19 ) of the threaded conveyor seal causes through the threads ( 28 ) in the centrifuge drum surface ( 3 ) a counteracting the negative pressure in the dryer conveying effect ( 29 ) and a gas back pressure, which prevents the penetration of incorrect air into the dryer interior.

Fig. 4 shows a non-contact seal with a pointed thread ( 31 ) which rotates with a narrow gap ( 19 ) within a soft cylindrical surface ( 32 ). The conveying effect of the thread seal compensates for the negative pressure in the dryer. The sliding housing ( 15 ) is compensated for in the gap by the sliding block ( 30 ).

The slide ring itself is sealed by heat-resistant O-rings both on the dryer end wall ( 15 ) and on the rigidly attached sealing ring ( 17 ).

Fig. 5 shows a non-contact seal with flat grooves, which rotates in a soft cylinder liner ( 32 ) made of plain bearing materials with a very narrow gap ( 19 ). The sliding movement of the front wall ( 15 ) of the dryer housing is compensated for by a sliding ring ( 34 ) which is resilient in the radial and axial directions.

Claims (8)

1. Housing seal for a dewatering device for dewatering and drying sludge with a centrifuge, preferably a solid bowl screw centrifuge, with an inlet for the supply of the sludge-like solid-liquid mixture and with at least one outlet each for the separated liquid and the dewatered thick matter, wherein the thick matter discharge zone of the centrifuge, the dispersion element of a spray dryer forms its stationary dryer housing which surrounds the centrifuge drum, with means for deflecting the trajectory of the thick matter particles radially thrown off in dispersed form as particle veils in the axial direction of the solid bowl centrifuges, characterized in that the seal for the displaceable Dryer housing opposite the rotating centrifuge drum, on the one hand from a rotary seal between rotating and non-rotating active surfaces, on the other hand from an axially and radially slidable ver There is a static part, whereby the rotary seal is not attached to the dryer housing, but is connected to the housing via displaceable sealing elements. 2. Housing seal according to claim 1, characterized in that the rotation seal is attached to the same support as the centrifuge rotor, such as. B. on Frame, pillow block, centrate housing. 3. Housing seal according to claim 1, characterized in that the rotation seal a non-contact seal with a narrow sealing gap such as se is a labyrinth seal or threaded conveyor seal. 4. Housing seal according to claim 1, characterized in that the rotation seal a contact seal such as a mechanical seal which is not held by the dryer housing. 5. Housing seal according to claim 1 to 4, characterized in that the Rotary seal with elastic or sliding sealing elements with the Dryer housing is connected gastight. 6. Housing seal according to claim 1 to 5, characterized in that the Dryer housing through sealing elements opposite the rotary seal in axial and or in the radial direction is displaceable without the sealing gap of the rotary change. 7. Housing seal according to claim 5, characterized in that the dry nergehäuse with the rotary seal on a sliding ring and is tightly connected. 8. Housing seal according to claim 5, characterized in that the dry nergehäuse with the rotary seal can be moved over an elastic membrane and is tightly connected.